The present invention pertains to compounds containing a substituted 4-acyl-2-piperazinone moiety which are useful as light and heat stabilizers for organic materials and to stabilized compositions containing said compounds.
The hindered amine compounds having the 2,2,6,6-tetrasubstituted piperidinyl structure have long been known as effective light stabilizers for organic materials and have enjoyed considerable commercial success.
Such hindered amine light stabilizers are described in detail by H. J. Heller and H. R. Blattmann, Pure and Applied Chemistry, 36, 141-161 (1973).
Substituted 2-piperazinones useful as UV stabilizers for photodegradable plastics are described in U.S. Pat. Nos. 4,190,571; 4,292,240 and 4,298,737. The compounds clearly described therein all contain a secondary or tertiary amine group, which being strongly basic, makes said compounds unsuitable for many end-use applications. U.S. Pat. No. 4,190,571 mentions N-carboalkoxy (urethane) compounds in passing, but does not teach how such compounds might be prepared or what properties said urethane derivatives might possess.
Acylated hindered amine light stabilizers based on piperidine are described in U.S. Pat. Nos. 4,046,737 and 4,066,615.